Many states are in the process of shifting their Medicaid programs from a free-for-service (FFS) payment structure to capitated managed care. California, whose Medicaid population in 1996 represented 16.3% of the total national Medicaid population, has embarked on an initiative to move 3.2 million Medicaid recipients, 75% of whom are children, into managed care plans over the next few years. Implementation of mandatory Medicaid managed care may significantly affect the provision of primary care services to children. Home visitation services have been shown to improve access to care and appropriate use of services for children at risk for child abuse and neglect. This study aims to: 1) track the enrollment process into one of six plans participating in mandatory Medicaid managed care in San Diego Country for a cohort of families at risk for child abuse and neglect, 2) investigate the effect of enrollment into mandatory Medicaid managed care on access to, continuity with, and use of primary care services for young children in at risk families, 3) examine how managed care enrollment interfaces with other factors associated with use of primary care services, and 4) assess whether home visitation services provide a protective effect for children in at risk families with regard to access to health care. The sample includes 448 mothers and their infants, identified at delivery as at risk for child abuse and neglect, participating in a randomized clinical trial of home visitation services in San Diego County. Data will be collected from families at four month intervals and cross- referenced with County welfare and Medicaid data sets. The impact of the enrollment process and home visitation services on primary care services will be assessed within the context of a comprehensive multivariate model of sociodemographic, familial and organizational factors based on the Andersen and Aday access model. Dependent variables include regular sources of primary care, use of alternative sites of care, well-visits, sick visits based on site of care, and compliance with AAP recommendations for well-visits and immunization rates. Long-term objectives are to provide information to better guide health policy with respect to mandatory Medicaid managed care enrollment and the provision of primary care services for vulnerable children in poor, at risk families.